| First Author | Schneider N | Year | 2014 |
| Journal | J Biol Chem | Volume | 289 |
| Issue | 3 | Pages | 1815-24 |
| PubMed ID | 24307171 | Mgi Jnum | J:209531 |
| Mgi Id | MGI:5568040 | Doi | 10.1074/jbc.M113.517177 |
| Citation | Schneider N, et al. (2014) Functional properties of the retinal glutamate transporters GLT-1c and EAAT5. J Biol Chem 289(3):1815-24 |
| abstractText | In the mammalian retina, glutamate uptake is mediated by members of a family of glutamate transporters known as "excitatory amino acid transporters (EAATs)." Here we cloned and functionally characterized two retinal EAATs from mouse, the GLT-1/EAAT2 splice variant GLT-1c, and EAAT5. EAATs are glutamate transporters and anion-selective ion channels, and we used heterologous expression in mammalian cells, patch-clamp recordings and noise analysis to study and compare glutamate transport and anion channel properties of both EAAT isoforms. We found GLT-1c to be an effective glutamate transporter with high affinity for Na(+) and glutamate that resembles original GLT-1/EAAT2 in all tested functional aspects. EAAT5 exhibits glutamate transport rates too low to be accurately measured in our experimental system, with significantly lower affinities for Na(+) and glutamate than GLT-1c. Non-stationary noise analysis demonstrated that GLT-1c and EAAT5 also differ in single-channel current amplitudes of associated anion channels. Unitary current amplitudes of EAAT5 anion channels turned out to be approximately twice as high as single-channel amplitudes of GLT-1c. Moreover, at negative potentials open probabilities of EAAT5 anion channels were much larger than for GLT-1c. Our data illustrate unique functional properties of EAAT5, being a low-affinity and low-capacity glutamate transport system, with an anion channel optimized for anion conduction in the negative voltage range. |
